PFC Boost using Error Amplifier as transconductanc amplifier

[ljy4468]

Hi all

I have a question about error amplifier.
There are two way of implement error amp.
Transconductance amp. and convertional voltage-type amp.

Below is TI's datasheet

http://www.abacus.co.uk/jkcm/cache/fl0016340.pdf

'The advantage in using a transconductance amplifier is that the inverting input of the amplifier is solely determined by the external resistive-divider from the output voltage and not the transient behavior of the amplifier itself. This allows the VO_SNS pin to be used for sensing over voltage conditions.'

VO_SNS pin is inverting input of EA.

Now , I wonder why the inverting input of the amplifier is solely determined by the external resistive-divider & why inverting input pin is used for sensing OVP
ONLY possible in transconductance amplifier.

Someone give me an advise.

Regards.